S501-2-R 2A Ceramic Cartridge Fuse, 5 x 20mm, Speed F. Ceramic fuses are great for short-circuit protection of semiconductors such as thyristors, diodes and triacs. Available in a range of current ratings with varying resistance values, this range are reliable for a broad range of applications. Note that fuses with values greater than 6.3A using open type fuse holders is recommended, to reduce the risk of nuisance tripping at or near full rated current.